The invention relates to a nozzle arrangement for steel manufacturing furnaces, and particularly for steel mill converters, whose blast pipes are usually positioned especially in the base or floor plate, and penetrate the vessel case and lining. The nozzle arrangement consists of a multitude of individual blast pipes for the separate supply of powdery, gaseous reactive, additional, and/or protective agents.
Such nozzle arrangements serve the purpose of introducing fresh or live gases, such as air or technically pure oxygen; and further for introducing lime or an oxygen/lime suspension to form a slag layer. Also, the nozzles may be used to supply inert gases, such as argon or nitrogen, as well as hydrocarbon gases as protective gases for the blast pipes. The distribution of the nozzles in the furnace wall and/or in the furnace floor depends on the shape of the furnace, which, in turn, is adapted to the characteristics of the selected blast process.
German DE-Os No. 17 83 165 discloses an apparatus for feeding the blast holes in the floor of a converter under a pressure of over 3 bars with a subdivided wind accumulator arranged below the blast holes, and formed in such a way that the wind accumulator device consists of a multitude of circular manifolds in concentric arrangement. Each of the blast holes in the floor consists of a metal tube, usually copper. Each of these pipes ends in a funnel at the base and is provided with an injector. Thus, the number of the blast holes matches the number of the injectors. Such a device is not only involved, but also unsafe, since in case of disturbance of one of the injectors the blast portion of the pertinent floor area is reduced.
The present invention is based on the premise that such a great number of blast holes is not required for metallurgical reasons and is supported by the experience gained in the oxygen inflation process which operates efficiently with a single blast lance whereby rarely more than three blast holes are provided at the blast lance head. Based on this, the existence of a large number of blast holes is not considered a necessity for metallurgical reasons, and the great requirement of technical apparatus is considered a disadvantage. A further disadvantage is the difficulty in having to maintain and repair such a great number of blast holes.
The present invention provides a simpler arrangement of nozzles using a minimum of technical expenditure, especially with reference to the number of parts, as well as their maintenance, and the spare part stock. This is achieved by grouping several blast pipes together in a single device, and having spaces present between the individual blast pipes, and by encasing the group of blast pipes by means of a jacket connected to a separate material input pipe, which may be connected and disconnected. The first advantage is that operation is possible with one device only. Another advantage is the small technical expenditure, as the number of parts is considerably reduced. Accordingly, the expenditure for maintainence, and for spare part inventory drops as well. The group arrangement according to the invention, also makes it possible to distribute individual nozzle arrangements according to the invention, on the floor and/or in the walls of the steel manufacturing furnace. In addition, there is the essential advantage of being able to form new flow cross sections by means of the jacket, where, optionally, more than one medium may be applied in order to increase the endurance of the nozzle, or to influence the metallurgic process mechanically or chemically.
As a further advantage of the basic concept of the invention, provision is made for positioning the blast pipes spaced from each other in a circular or polygonal annular cross section. This allows for influencing the size and shape of the flow cross section existing between the individual blast pipes. In those instances, the blast pipes, with polygonal annular cross section, touch with cross section angles and/or with cross section sides. In this way, flow cross section of uniform shape and/or size may be utilized for additional media practically between the blast pipes.
The invention is further characterized by its use in an oxygen inflation converter with a blast lance which may be lowered from above through the converter nozzle and by its eccentric arrangement to the blast lance axis in the floor area of the converter. The invention is thus suitable for the combination of two differential steel manufacturing procedures, viz. the LD process with the so-called OBM process (QBOP process).
Another improvement of the invention is the fact that for a group of blast pipes, a material feeding pipe is provided which is concentric to a nozzle case and whose distributer chamber is sealed against an outer annular chamber, and that the jacket is connected to the annular chamber which, in turn, is connected to another material feeding pipe. This arrangement gives preference to the materials which go through the blast pipes, thus resulting in a distribution favorable to the flow, while, for example, shell or jacket gases, and the like, are brought to the peripheral areas of the blast pipes for distribution.
The special development of the nozzle arrangement of the invention consists in that the nozzle case is essentially formed by one base plate receiving the blast pipes and/or the plug-in nozzles for the pipes, and one flange plate provided with a shaft portion forming the concentric distributer chamber. Also, one case part forms, together with the shaft portion the annular chamber where the jacket is connected. A very tight connection of the jacket can be achieved by providing an opening in the base plate for the connection of the jacket. Furthermore, the invention provides, between the base plate and the shaft part of the flange plate, an interchangeable nozzle plate to be plugged onto the blast pipes.